A characterisation of thick film resistors for strain gauge applications

Some commercial thick film resistors with sheet resistivities from 1 kohm/sq. up to 1 Mohm/sq. were evaluated for strain gauge applications. Temperature coefficients of resistivity, noise indices and gauge factors (GFs) were measured. For the same resistor series GFs and noise indices increase with increasing sheet resistivity. However, both GFs and noise indices are different for resistors with the same nominal sheet resistivity but from different resistor series. The results indicated that the microstructure rather than the different chemical composition of the conductive phase in thick film resistors is the primary reason for the different gauge factors.     

Road lighting energy-saving system based on wireless sensor network

An intelligent wireless sensor network that is designed to save road lighting energy, while maintaining traffic safety, is presented. It consists of an array of nodes that may be installed on both sides of the road, being mutually separated by a few tens to a few hundreds of meters. Each node consists of (i) vehicle detection subsystem, (ii) wireless communications and control subsystem for message exchange between the neighboring nodes, and (iii) lighting subsystem. During the day, nodes are inactive, while during the night, they turn to an active mode enabling detection of passing vehicles and timely activation of road lighting. Upon detection of a passing vehicle, the node generates a wireless message. Neighboring nodes that receive the wireless message will turn on their road lighting. In order to prevent driver distraction, each lamp will be turned on at a safe distance ahead of the moving vehicle. In order to improve energy efficiency, the lights will be dimmed or turned off behind the passing vehicle. The proposed road lighting energy-saving (RLES) system, which combines advanced sensor and wireless communication technologies, is suitable for implementation both with existing high-intensity discharge (HID) lamps and new light-emitting diode (LED) lamps. Our analysis shows that the RLES system will pay off in less than a year when used with HID lamps, while pay-back period is less than two and a half years when used with LEDs.